1. Field of the Invention
The present invention relates to a steering tilt column assembly for a vehicle, and in particular to a steering tilt column assembly for a vehicle which is capable of implementing a stable engaged state of an engaged fixing gear and driving gear for continuing a tilting state, removing some parts by directly operating an upward rotation operation of a driving gear using a tilt lever, preventing a noise and loosening by preventing a bolt used for a lever hinge of a tilt lever from affecting to a rotation friction during a rotation of a tilt lever, increasing an impact absorbing effect and unit cost by improving a material and structure of an initial impact absorbing capsule used for a mounting bracket, and implementing an impact absorbing and fixed engagement without using a dual column by making an engaging structure of a lower portion of a column and a lower bracket have a cross sectional portion with a decreased diameter.
2. Description of the Background Art
Generally, a vehicle steering tilt column assembly is installed in an outer portion of a steering shaft 20 adapted to transfer a rotational force from a steering wheel to a gear box for thereby supporting a rotation of the same and connecting to a vehicle body.
FIG. 1 is a view illustrating a conventional steering tilt column assembly.
As shown in FIG. 1, a unit for connecting a steering tilt column assembly to a vehicle body includes a mounting bracket 70 fixed in an intermediate position of the column 10, a capsule 80 inserted into a slot at both sides of the mounting bracket, and a lower bracket 90 which is fixed in a lower position of the column 10 formed of an outer tube 10a and an inner tube 10b, namely, in a lower portion of the inner tube 10b. 
The steering shaft 20 includes an upper and lower ends connected with a steering wheel and a gear box, respectively, and is connected with a universal joint adapted to transfer a rotational force in a bent state therebetween.
In addition, the steering column adapted to support the steering shaft includes a tilting apparatus adapted to maintain a bent state of the steering shaft and to adjust an angle of a steering wheel based on a driver's physical state.
FIG. 2 is a view illustrating the above tilting apparatus.
Here, a column bracket 30 is installed in an upper portion of the steering column 10. A tilt bracket 40 is installed in an outer portion at both sides of the column bracket 30 for surrounding the same. The column bracket 30 and the tilt bracket 40 are connected with both ends of the split steering shaft 20, respectively.
In addition, both sides of the column bracket 30 and the tilt bracket 40 are engaged to the tilt hinge 32, respectively, and when the steering shaft 20 installed in the interior of the same is bent, the same is bent by the universal joint (not shown) based on a cooperation of the same.
A circular shaped fixing gear 31 which as the same center as the tilt hinge 32 and a threaded portion in an outer surface of the same is installed in an outer one side of the column bracket 30. A driving gear 41 is formed in the tilt bracket 40 and is engaged with the fixing gear 31.
Namely, one end of the driving gear 41 is engaged to the gear hinge 42 in the tilt bracket 40, and a threaded portion engaged with a threaded portion of the fixing gear 31 is formed in an inner surface of the front end of the same and is elastically supported by a spring (not shown) based on a continuous engagement.
In addition, the tilt bracket 40 has a certain structure capable of rotating the driving gear 41 for angling the column bracket 30, the tilt bracket 40 and the steering shaft 20 by distancing the engaged driving gear 41 and the fixing gear 31.
Namely, there is provided a driving pin 43 protruded in one side of the driving gear 41. A rotation member 50 is installed in a lower side of the driving pin 43 for thereby lifting the driving gear 41 through the driving pin 43. The rotation member 50 is rotatably installed by the tilt hinge 32 at its center.
At this time, the rotation member 50 is installed between the tilt bracket 40 and the column bracket 30 in such a manner that opposite bent both ends of the same are passed through by the tilt hinge 32, and the intermediate portion of the same covers an outer surface of the driving gear 41. A rotation portion 51 is formed in a lower side of the driving pin 43.
The portion in which the rotation portion 51 of the rotation member 50 is formed is connected with the gear hinge 42 which is a rotation point of the driving gear 41 and is recovered after the operation of the rotation member 50. A recovering spring 54 is installed so that the tilt bracket 40 and the column bracket 30 are bent and recovered to their original positions.
Another recovering spring 55 is installed in the opposite portion of the recovering spring 54 with respect to the tilt hinge 32 so that the tilt bracket 40 and the column bracket 30 are bent to the other side and then are recovered.
In addition, A connection portion 52 which is longitudinally extended in the direction of the tilt bracket 40 and is bent is formed in the portion opposite to the rotation portion 51 of the rotation member 50. The above connection potion 52 is connected through an end portion of the tilt lever 60 in which an intermediate portion is rotatably fixed in the lever hinge 61 formed in the tilt bracket 40 and the connection spring 53.
Therefore, when pulling the handle of the tilt lever 60, an end portion of the tilt lever 60 pushes the connection portion 52, and the rotation member 50 is rotated. Therefore, the rotation portion 52 lifts up the driving gear 41, and the driving gear 41 and the fixing gear 31 are distanced for thereby implementing a tilting function.
The steering tilt column assembly has an impact absorbing structure.
As one of the functions, it is directed to implementing an initial impact absorbing function. There are provided a capsule 80 inserted into the mounting bracket 70, and a collapsing structure capable of implementing an impact absorbing function in the lower mounting portion.
As shown in FIG. 1, in the latter case, the steering column 10 is engaged with two hollow tubes of an outer tube 10a and an inner tube 10b for thereby contracting when an impact is transferred.
However, the conventional vehicle steering column tilting apparatus has the following problems.
First, since there are not any structure and apparatus for supporting the engagement of the fixing gear and the driving gear, the driving gear and the fixing gear are easily distanced when an external impact is transferred.
Namely, in the case that an abnormal external force or vibration occurs, since there is not any member for continuously preventing by pressing the driving gear 41 in the direction of the fixing gear 31, the driving gear 41 may be lifted up for thereby unlocking the locked state.
Second, the rotation member 50 is installed between the tilt bracket and the column bracket using a tilt hinge for thereby lifting the driving gear 41. However, the rotation member is formed of a thin steel plate rotating. Therefore, the strength is weak, and the rotation member 50 may be bent when an external impact is transferred, so that a pop-up problem (steering wheel is popped up) may occur. Furthermore, the rotation member 50 may be omitted by improving the structure.
Third, as shown in FIG. 1, in the steering column tilting apparatus, a common bolt 61a is engaged in the lever hinge 61 for rotatably fixing the tilt lever 60 in the tilt bracket 40.
The engagement of the bolt 61a will be described. As shown in FIG. 4, there are needed a plate 60b, a rivet 60a, a bolt 61a and a lever 60. In addition, a work process such as a bolt riveting portion of a tilt bracket is needed. Therefore, the fabrication cost is increased.
In addition, since the upper surfaces of the bolt 61a and the tilt lever 60 closely contacted, and the lower surface of the tilt lever 60 and the upper surface of the tilt bracket 40 are closely contacted, when the bolt 61a is strongly tightened, when the tilt lever 60 is rotated, a friction force is increased, so that it is difficult to handle. In addition, the bolt is too loosely tightened, a noise occurs, and the bolt 61a is gradually loosened.
Fourth, there are problems in the capsule 80 adapted to fix the mounting bracket 70 to a vehicle body and a structure for assembling the capsule.
In the mounting bracket 70, an intermediate portion of the same surrounds the upper side of the steering column 10, and an expanding portion 71 is formed in extended both sides and is opposite to the vehicle body. A slot 42 which is opened in the upper side is formed in the expanding portion 71. In addition, the capsule 80 is formed by injecting aluminum. An insertion groove 81 is formed in both sides in order for an outer surface of the slot 72 to be inserted thereinto. A bolt hole 82 is formed in the center, so that the bolt 84 passes through the same and is fixed to the vehicle body.
As shown in FIG. 3, a plurality of capsule holes 83 and slot holes 73 which pass through the upper and lower sides are formed in the engaged outer surfaces of the capsule 80 and the slot 72. A plastic melting material is injected in the interior of the same for thereby hardening the same and forming a pin shape.
Namely, the hardened plastic melting material connects the capsule 80 fixed to the vehicle body and the mounting bracket 70 fixed to the steering column 10. When an external impact is applied to the steering column 10, the plastic melting material is broken, so that the steering column 10 is separated from the capsule 80.
However, in the escaping apparatus of a conventional steering column, the capsule and the basic structure of the mounting bracket engaged thereto are complicated. In addition, a complicated process for injecting a plastic melting material and hardening the same in the slot hole communicating with the capsule hole formed in the capsule is needed. Therefore, the installation process is complicated, and the fabrication cost is increased.
Furthermore, when managing the weights using a fixing pin formed of plastic, since the weight managing limit is low based on the property of the material, the applicable range is limited. In order to overcome the above problems, when the number and thickness of the fixing pin are adjusted, the structure may be more complicated.
Fifth, there is a problem in the impact absorbing structure formed of the steering column 10 and the lower bracket 90 adapted to support the lower portion of the steering column.
The important points of the impact absorbing structure are that a lower bracket should be used for fixing the lower portion of the column to the vehicle body. Since the lower bracket of the lower portion of the column is integrally welded, an additional inner tube must be used for implementing an impact absorbing structure. In addition, the lower bracket must be welded to the lower portion of the inner tube.
FIG. 1 is a view illustrating the conventional impact absorbing structure.
Namely, a collapsing problem occurs between the outer tube 10a which surrounds the steering shaft 20 and the inner tube 10b fixed to the lower bracket for thereby absorbing an impact energy when a vehicle collides. The inner tube 10b is fixed to the vehicle body by the lower bracket 90, and one end of the same is engaged to an inner surface of the outer tube 10a. A plurality of curling portions 10c are formed along an outer circumference in the inner surface of the outer tube 10a. 
In particular, the above formation of the curling potion 10c is performed in such a manner that the portions remaining piercing operations are formed in the outer tube 10a are inwardly rolled. The above curling portion 10c is assembled to the end portion of the inner tube 10b for thereby implementing a friction force.
Therefore, when an impact energy is applied through the steering shaft 20 when a vehicle collides, the end portion of the inner tube 10b of the lower mounting portion makes a friction with the curling portion 10c of the outer tube 10a, so that a collapsing operation is performed for thereby absorbing the impact energy.
However, in the above structure, when the outer tube 10a and the inner tube 10b are assembled, the curling portion 10c may be broken based on the material for thereby causing an error product. In particular, the process for forming the curling portion 10b in the outer tube 10a is very complicated. In addition, the inner tube must be added. Therefore, the number of parts is increased.